drm/i2c: tda998x: configure both fields of AIP_CLKSEL together

We can configure both fields of the AIP_CLKSEL register with a single
write, there is no need to delay the setting of the CTS reference.

Tested-by: Sven Van Asbroeck <TheSven73@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>